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Date: Sun, 30 May 2010 19:03:46 +0200
From: Borislav Petkov <bp@alien8.de>
Subject: [PATCH] x86, hweight: Fix UML boot crash
Message-ID: <20100530170346.GC1565@liondog.tnic>
References: <201005271944.09541.toralf.foerster@gmx.de>
 <AANLkTimKwxYxM_PExplIDK1WPTQ9e_-CHn5SnIvfjfUg@mail.gmail.com>
 <20100530150214.GA1565@liondog.tnic>
 <201005301728.25976.toralf.foerster@gmx.de>
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In-Reply-To: <201005301728.25976.toralf.foerster@gmx.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>, Borislav Petkov <borislav.petkov@amd.com>, Toralf =?utf-8?Q?F=C3=B6rster?= <toralf.foerster@gmx.de>, user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
List-ID: <user-mode-linux-devel.lists.sourceforge.net>

Obviously UML cannot stomach callee reg-saving trickery
introduced with d61931d89be506372d01a90d1755f6d0a9fafe2d (x86:
Add optimized popcnt variants) and oopses during boot:
http://marc.info/?l=linux-kernel&m=127522065202435&w=2

Go ahead and fall back to the software hweight* routines on UML.

LKML-Reference: <201005271944.09541.toralf.foerster@gmx.de>
Tested-by: Toralf Förster <toralf.foerster@gmx.de>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Borislav Petkov <bp@alien8.de>
---
 arch/x86/include/asm/bitops.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 545776e..c9dad12 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -444,7 +444,11 @@ static inline int fls(int x)
 
 #define ARCH_HAS_FAST_MULTIPLIER 1
 
+#ifdef CONFIG_UML
+#include <asm-generic/bitops/arch_hweight.h>
+#else
 #include <asm/arch_hweight.h>
+#endif
 
 #include <asm-generic/bitops/const_hweight.h>
 
-- 
1.7.1

-- 
Regards/Gruss,
    Boris.